Coordinated Channel Access Techniques for Sidelink Communications

1. A method for wireless communication at a first user equipment (UE), comprising: receiving an indication of a set of available resources for communications with a second UE using a unicast connection via a sidelink channel; transmitting, to the second UE, an indication of a pattern of resources within the set of available resources, the pattern of resources including at least a first subset of time domain resources in which the first UE has a higher priority than the second UE for initiating a channel access procedure for access to the sidelink channel in accordance with the channel access procedure, wherein the channel access procedure includes a listen before talk (LBT) procedure that indicates channel availability of a shared radio frequency spectrum band that contains the set of available resources, and wherein the first UE uses first LBT parameters that provide a higher probability of channel access than second LBT parameters of the second UE for the first subset of resources; and communicating with the second UE via the sidelink channel, wherein access to the sidelink channel is based at least in part on the channel access procedure and the pattern of resources.

2. The method of claim 1, wherein the transmitting comprises: transmitting a time domain pattern of resources to the second UE, wherein the first subset of resources include a subset of time domain intervals within the set of available resources.

3. The method of claim 1, wherein the second UE is to refrain from initiating the channel access procedure within the first subset of resources.

4. The method of claim 1, further comprising: selecting a first contention window duration associated with the channel access procedure, and wherein the first contention window duration is shorter than a second contention window duration of the second UE; and initiating the channel access procedure based at least in part on the first contention window duration.

5. The method of claim 1, wherein the transmitting comprises: transmitting a preferred resource indication to the second UE that identifies resources that are available for the second UE to perform the channel access procedure.

6. The method of claim 5, wherein the first subset of resources are associated with resources that are non-preferred resources at the second UE and the second UE is to refrain from performing the channel access procedure in the non-preferred resources.

7. The method of claim 1, wherein the first LBT parameters include a first energy detection (ED) threshold that is higher than a second ED threshold of the second LBT parameters.

8. The method of claim 1, wherein the first UE uses a lower channel access priority class (CAPC) for the channel access procedure than a CAPC of the second UE.

9. The method of claim 1, wherein the first UE uses a longer cyclic prefix (CP) duration from a first automatic gain control symbol in the first subset of resources than a CP duration of the second UE.

10. The method of claim 1, further comprising: transmitting, to the second UE, a channel occupancy time (COT) sharing indication that indicates the second UE can attempt channel access in a COT that the first UE obtained, and wherein the second UE is to refrain from performing the channel access procedure in an absence of the COT sharing indication.

11. The method of claim 1, wherein the first UE uses a channel access priority class (CAPC) that provides a shorter deferral value or a smaller contention window for the channel access procedure than the second UE.

12. The method of claim 1, further comprising: determining to prioritize the first UE for the first subset of resources based at least in part on a number of connections with other UEs that are served at the first UE.

13. The method of claim 1, further comprising: transmitting, to the second UE, a reconfiguration message that indicates a changed priority associated with one or more subsets of resources of the set of available resources.

14. The method of claim 1, further comprising: transmitting, responsive to obtaining channel access based on the channel access procedure, a channel occupancy time (COT) sharing indication to the second UE that indicates the pattern of resources within an obtained COT in which the first UE has a higher priority than the second UE for initiating the channel access procedure.

15. An apparatus for wireless communication at a first user equipment (UE), comprising: a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: receive an indication of a set of available resources for communications with a second UE using a unicast connection via a sidelink channel; transmit, to the second UE, an indication of a pattern of resources within the set of available resources, the pattern of resources including at least a first subset of time domain resources in which the first UE has a higher priority than the second UE for initiating a channel access procedure for access to the sidelink channel in accordance with the channel access procedure, wherein the channel access procedure includes a listen before talk (LBT) procedure that indicates channel availability of a shared radio frequency spectrum band that contains the set of available resources, and wherein the first UE uses first LBT parameters that provide a higher probability of channel access than second LBT parameters of the second UE for the first subset of resources; and communicate with the second UE via the sidelink channel, wherein access to the sidelink channel is based at least in part on the channel access procedure and the pattern of resources.

16. The apparatus of claim 15, wherein the instructions to transmit are executable by the processor to cause the apparatus to: transmit a time domain pattern of resources to the second UE, wherein the first subset of resources include a subset of time domain intervals within the set of available resources.

17. The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to: select a first contention window duration associated with the channel access procedure, and wherein the first contention window duration is shorter than a second contention window duration of the second UE; and initiate the channel access procedure based at least in part on the first contention window duration.

18. The apparatus of claim 15, wherein the instructions to transmit are executable by the processor to cause the apparatus to: transmit a preferred resource indication to the second UE that identifies resources that are available for the second UE to perform the channel access procedure.

19. The apparatus of claim 15, wherein the first LBT parameters include one or more of a first energy detection (ED) threshold that is higher than a second ED threshold of the second LBT parameters.

20. The apparatus of claim 15, wherein the first UE uses one or more of a lower channel access priority class (CAPC) for the channel access procedure than a CAPC of the second UE, or a longer cyclic prefix (CP) duration from a first automatic gain control symbol in the first subset of resources than a CP duration of the second UE.

21. The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to: transmit, to the second UE, a channel occupancy time (COT) sharing indication that indicates the second UE can attempt channel access in a COT that the first UE obtained, and wherein the second UE is to refrain from performing the channel access procedure in an absence of the COT sharing indication.

22. The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to: transmit, to the second UE, a reconfiguration message that indicates a changed priority associated with one or more subsets of resources of the set of available resources.

23. An apparatus for wireless communication at a first user equipment (UE), comprising: means for receiving an indication of a set of available resources for communications with a second UE using a unicast connection via a sidelink channel; means for transmitting, to the second UE, an indication of a pattern of resources within the set of available resources, the pattern of resources including at least a first subset of time domain resources in which the first UE has a higher priority than the second UE for initiating a channel access procedure for access to the sidelink channel in accordance with the channel access procedure, wherein the channel access procedure includes a listen before talk (LBT) procedure that indicates channel availability of a shared radio frequency spectrum band that contains the set of available resources, and wherein the first UE uses first LBT parameters that provide a higher probability of channel access than second LBT parameters of the second UE for the first subset of resources; and means for communicating with the second UE via the sidelink channel, wherein access to the sidelink channel is based at least in part on the channel access procedure and the pattern of resources.

24. The apparatus of claim 23, wherein the means for the transmitting comprise: means for transmitting a time domain pattern of resources to the second UE, wherein the first subset of resources include a subset of time domain intervals within the set of available resources.

25. The apparatus of claim 23, wherein the means for the transmitting comprise: means for transmitting a preferred resource indication to the second UE that identifies resources that are available for the second UE to perform the channel access procedure.

26. A non-transitory computer-readable medium storing code for wireless communication at a first user equipment (UE), the code comprising instructions executable by a processor to: receive an indication of a set of available resources for communications with a second UE using a unicast connection via a sidelink channel; transmit, to the second UE, an indication of a pattern of resources within the set of available resources, the pattern of resources including at least a first subset of time domain resources in which the first UE has a higher priority than the second UE for initiating a channel access procedure for access to the sidelink channel in accordance with the channel access procedure, wherein the channel access procedure includes a listen before talk (LBT) procedure that indicates channel availability of a shared radio frequency spectrum band that contains the set of available resources, and wherein the first UE uses first LBT parameters that provide a higher probability of channel access than second LBT parameters of the second UE for the first subset of resources; and communicate with the second UE via the sidelink channel, wherein access to the sidelink channel is based at least in part on the channel access procedure and the pattern of resources.

27. The non-transitory computer-readable medium of claim 26, wherein the instructions are further executable by the processor to: select a first contention window duration associated with the channel access procedure, and wherein the first contention window duration is shorter than a second contention window duration of the second UE; and initiate the channel access procedure based at least in part on the first contention window duration.

28. The non-transitory computer-readable medium of claim 26, wherein the instructions are further executable by the processor to: transmit, to the second UE, a reconfiguration message that indicates a changed priority associated with one or more subsets of resources of the set of available resources.